A housing of this type is already known from EU 0 258 491 A1. Moreover, reference is made to EU 0 025 478 A1 and to EU 0 025 472 A1. Moreover, the present Applicant knows of a sash lock for a sheet metal cabinet door in which the screw holding the sash tongue also holds a spring which is bent in a U-shape and contacts the rear surface of the door leaf with the free end of its leg and, in so doing, secures the housing in the aperture. In a manner similar to that known from EU 0 258 491 A1, the latter arrangement can be mounted without a cumbersome screwing on of nuts or attachment of fastening springs in that the sash lock can be fastened by simply inserting the housing into the door lock aperture as far as the flange. In EU 0 025 478 A1, on the other hand, the fastening of the lock housing is only possible in that a fastening spring is inserted into a corresponding circumferential groove of the housing on the back of the wall after the insertion of the housing.
For the rest, such sash locks previously worked for the most part with screw-type fastening which requires that the fastening nut be placed on and then tightened from the rear after inserting the housing through the wall aperture. This has the disadvantage, as is the case with fastening by means of a plug-in spring, that it requires a special structural component part which is separate from the housing and which can also be lost. In addition, a blind fastening is not possible here in cases where the back of the wall is not easily accessible.
This disadvantage does not occur in a blind fastening according to the lock known to the Inventor, but the lock known to the Inventor has the disadvantage that the fastening spring transmits its pressure load to the support of the sash tongue and accordingly leads to unwanted high friction and hindrance of the locking process. An improvement is made this respect in EU 0 025 478 A1, in which the back of the wall likewise need not be accessible for mounting the lock housing, since the springs arranged at the housing contact behind the wall after the housing is inserted through the wall aperture and fix the housing so as to lock it. In addition, there is no loading of the sash axis in this case, since the fastening forces are transmitted directly to the lock housing.
However, the construction known from EU 0 258 491 A1 obviously requires an aperture other than the conventional aperture (round hole with two or four conventional flattened portions serving as protection against rotation). For example, FIG. 4 of EU 0 258 491 A1 shows an aperture with additional recesses 31 provided in the region of two flattened portions. The other embodiment forms of EU 0 258 491 A1 (see FIGS. 9, 13) also require such additional recesses which increase production costs and interfere with the compatibility of locks which are already commercially available. In the embodiment forms according to FIGS. 5 and 6, apertures departing from the round shape are obviously not required. But these embodiment forms are not directed to a lock housing, but rather to sleeves for receiving such housings. Accordingly, lateral apertures are required for holding the lock housing, which leads to sealing problems if the arrangement is to be used in a sheet metal cabinet or sheet metal housing to be sealed.
A lock with grounding and/or fastening springs in the form of a sash lock is already known from the European Patent Publication 0 025 472. A disadvantage in the latter consists in that in order to fasten the lock in the sheet metal wall a spring which is separate from the lock housing and is bent in a U-shaped manner as seen from above must be attached to the housing, which is provided with lateral grooves, from behind after inserting the lock through the sheet metal wall aperture from the front in order to effect the fastening process and the grounding process.
However, a blind mounting of such a lock is also desirable in this case. Also, the known lock is not sufficiently resistant to shaking in many cases, i.e. the inserted spring can be removed again from its inserted position during strong vibration stresses, thus releasing the lock.